Alaska weather geeks, including me, will soon have more to gawk
at. The state's offices of the National Weather Service are switching
to a new communication system that will

The interior Alaska
sky during a chinook, a phenomenon that occurs when air from
south of the Alaska Range warms rapidly on its descent of the
north side of the mountains.
Photo by Ned Rozell...

someday allow people to
check forecasts for their specific neighborhood or village.

Forecasters at weather service
offices in Juneau, Anchorage and Fairbanks have started to use
a computer database that divides Alaska's 912,597 square kilometers
into individual boxes about three-to-five kilometers on a side.
As soon as the bugs are worked out of the system, Alaskans will
be able to select specific areas of the state and get detailed
forecasts.

"Say you want to go hunting
70 miles west of Iliamna and you want to know what the weather
will be like in two days," said Eric Stevens of the NWS
office in Fairbanks. "Instead of settling for a generalized
forecast for the entire region around Iliamna, you could click
on a point on the map, and boom, there's your customized information.
We have the potential to forecast for every 5-kilometer 'neighborhood'
in Alaska."

A few weeks ago, Stevens and
his colleagues at the Fairbanks office changed to the "Interactive
Forecast Preparation System," now in use by the National
Weather Service nationwide. The new system divides Alaska into
fine grids and allows forecasters to add localized information
that affects weather, such as the slope direction of hills.

The new system allows weather
service forecasters to produce maps of Alaska color-coded for
temperature, wind speed, chance of precipitation and other weather
variables, such as the size of waves expected on the open ocean.
The Juneau office of the National Weather Service currently offers
experimental versions of those maps at http://pajk.arh.noaa.gov/fcstgrids.php,
and the Fairbanks and Anchorage offices should have the graphical
information available for the remainder of Alaska and its surrounding
waters by the end of summer 2004, Stevens said.

While the weather service's
method of communicating the weather is changing, the way forecasters
predict the weather remains the same. To develop a forecast,
they use satellite and radar images of Alaska, ground and weather
balloon measurements, and computer models. To issue long-range
forecasts that extend seven days, forecasters depend on computer
models that provide simulations of Earth's weather from real-life
inputs, such as information on temperatures and wind speeds from
weather balloons. Taking this data on the current state of the
atmosphere, computers crunch millions of numbers and, accounting
for the laws of physics, give possible solutions for the future
weather situation. While the models alone do a poor job of forecasting
the weather, forecasters use the other tools at their disposal
to make detailed seven-day predictions, which they update constantly
as conditions change.

Besides considering the output
of a few high-power computer models, forecasters use three other
main methods to predict the weather, Stevens said. The first
is observing the current weather and estimating how long it will
persist. Another is climatology-looking at historical records
for Alaska and seeing the temperatures of certain days in the
past and finding a range that might be accurate. The most important
element is human experience, Stevens said. When a forecaster
has predicted weather in an area for 20 years, he or she knows
the meteorological quirks of the place and how best to interpret
information from computer models and other sources.

This column is provided as
a public service by the Geophysical Institute, University of
Alaska Fairbanks, in cooperation with the UAF research community.
Ned Rozell is a science
writer at the institute